zephyr nrf5340dk Unable to set external PINs, e.g. GPIO P0.00 as GPIO OUT pin

[walkingcode]

When PIN=0 P0.00 is used it doesn't work (No error message or failing, i also tried several other ports), no toggling output.
The code works with PIN=28 (P0.28=LED1), led is blinking.
If i try it with the PIN=0 P0.00 it doesn't (No error message, i also tried several other ports).

What's wrong ?

void main() {
    const struct device *dev0;
    const int PIN=0; // 28 (=led1 is working)
    bool led_is_on = true;
    int ret;

    dev0 = DEVICE_DT_GET(DT_NODELABEL(gpio0));

    if (dev0==NULL) {
        printk("device not found");
        return;
    }

    if (!device_is_ready(dev0)) {
        printk("GPIO controller not ready");
        return -ENODEV;
    }
    gpio_pin_configure(dev0, PIN, GPIO_OUTPUT);
    while(1) {
        gpio_pin_toggle(dev0, PIN);
        k_msleep(SLEEP_TIME_MS);
    }
}

prj.conf
CONFIG_GPIO=y

[Vidar Berg]

Hello,

If you look at the silkscreen on the backside, you can see that P0.00 and P0.01 are connected to the 32 KHz by default. Have you cut and shorted the solder bridges described here: 32.768 kHz crystal. You will also need to select the internal RC oscillator as the 32KHz clock source if you are going to use these pins as GPIOs.

Kconfig symbol to select the internal RC oscillator: https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/kconfig/index.html#CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC

Best regards,

Vidar

[walkingcode]

It works. Many, many thanks for your fast and helpful response.

I wasn't forced to use P0.00, i could use any, so now i use P0.10. Are there any general recommendations which custom GPIO should be used ? I also tried to configure the pin with the gpio_pin_configure_dt function, but i didn't get it. How can e.g. the P0.10 be configured via device tree ?

[Vidar Berg]

No problem.  P0.10 is actually not available by default either as it is connected to the NFC antenna by default (please also refer to the NFC Pin configuration section of the PS for limitations that applies to these pins). The quickest way to get an overview of the pin assignments for the DK is to have a look at the silkscreen.